News
News
Industry News
您的位置：主页 > News > Industry News >
Performance Analysis of Triple Eccentric Butterfly Valve
发布时间：2018-10-18 来源：艾德威尔•瑞拓
The spatial structure of the Triple Eccentric Butterfly Valve discs is complex, and the force and displacement distribution of the disc directly affects the sealing of the butterfly valve and the opening and closing of the valve. If the deformation of the disc is unreasonable, it will directly affect the sealing effect of the valve, leading to leakage, and self-locking may occur.
The sealing pair of the triple eccentric butterfly valve is usually a tapered surface, and its structure is shown in FIG. The butterfly plate in the figure is obtained by obliquely cutting the cone. The O point is the origin of the reference coordinate system, the O' point is the center of the eccentric disc, the cone half angle is β, and the three eccentricities are: the cone axis x' and the flow channel center line x The angle eccentricity α, the eccentric disc rotation center O' and the radial eccentricity α of the x-axis of the flow center line and the eccentric disc rotation. The center O' and the axial eccentricity e of the midplane of the disc. The angle γ is the angle between the sealing surface of the disc and the x-axis of the center line of the flow channel, and the angle changes continuously along the orientation of the rotation of the sealing surface. In the figure, the γ angles at the lower ends of the disc are γ1 and γ2, respectively.
Under working conditions, the medium pressure and the closing torque applied by the valve stem work together on the disc. The support of the edge sealing surface of the disc makes the disc balance the force. The valve stem also supports the disc and can offset the pressure of a part of the medium. . The flow direction of the medium in the triple eccentric butterfly valve is divided into positive flow and reverse flow. When the medium is reverse flow, the medium pressure and the torque of the valve stem will weaken each other, so that the force of the butterfly plate is reduced; and when the medium is positive (the positive along the x-axis) Direction), the medium pressure and the torque of the stem will overlap each other, increasing the force on the disc. Therefore, the condition of the medium should be taken and the disc should be analyzed.
In the positive flow state, the disc is affected by the combination of the medium force, the force of the valve stem and the supporting force of the sealing surface. The support force and deformation distribution of the edge of the disc directly affect the sealing and opening and closing performance of the disc. Therefore, the mechanical model of the disc is simplified and the edge of the disc is analyzed. As shown in Fig. 2, the ellipse of the disc rotates around the y' axis of the center of rotation, and is balanced by the medium pressure and the torque of the valve stem, and the supporting force of the sealing surface (simplified to an elliptical line) is balanced. The connection between the valve stem and the disc is taken at a central portion far from the sealing surface, so that the influence on the rigidity of the sealing surface is reduced. The force of the joint of the disc can be neglected, focusing on the superposition of the medium pressure on the elliptical surface and the torque of the valve stem, and the effect on the pressure acting on the sealing surface.
The three eccentric butterfly valve are plate-like structures, and the middle part can be analyzed according to the plate problem. However, the spatial structure of the edge of the disc is more complicated, and the stress and deformation distribution on the edge have a great influence on the performance of the butterfly valve. The degree of fit of the sealing surface and the smoothness of the opening and closing are related to the force displacement distribution of the edge of the disc. In this paper, the edge of the disc is taken as the focus of analysis, and the load of the disc is deduced and calculated.
The sealing pair of the triple eccentric butterfly valve is usually a tapered surface, and its structure is shown in FIG. The butterfly plate in the figure is obtained by obliquely cutting the cone. The O point is the origin of the reference coordinate system, the O' point is the center of the eccentric disc, the cone half angle is β, and the three eccentricities are: the cone axis x' and the flow channel center line x The angle eccentricity α, the eccentric disc rotation center O' and the radial eccentricity α of the x-axis of the flow center line and the eccentric disc rotation. The center O' and the axial eccentricity e of the midplane of the disc. The angle γ is the angle between the sealing surface of the disc and the x-axis of the center line of the flow channel, and the angle changes continuously along the orientation of the rotation of the sealing surface. In the figure, the γ angles at the lower ends of the disc are γ1 and γ2, respectively.
Under working conditions, the medium pressure and the closing torque applied by the valve stem work together on the disc. The support of the edge sealing surface of the disc makes the disc balance the force. The valve stem also supports the disc and can offset the pressure of a part of the medium. . The flow direction of the medium in the triple eccentric butterfly valve is divided into positive flow and reverse flow. When the medium is reverse flow, the medium pressure and the torque of the valve stem will weaken each other, so that the force of the butterfly plate is reduced; and when the medium is positive (the positive along the x-axis) Direction), the medium pressure and the torque of the stem will overlap each other, increasing the force on the disc. Therefore, the condition of the medium should be taken and the disc should be analyzed.
In the positive flow state, the disc is affected by the combination of the medium force, the force of the valve stem and the supporting force of the sealing surface. The support force and deformation distribution of the edge of the disc directly affect the sealing and opening and closing performance of the disc. Therefore, the mechanical model of the disc is simplified and the edge of the disc is analyzed. As shown in Fig. 2, the ellipse of the disc rotates around the y' axis of the center of rotation, and is balanced by the medium pressure and the torque of the valve stem, and the supporting force of the sealing surface (simplified to an elliptical line) is balanced. The connection between the valve stem and the disc is taken at a central portion far from the sealing surface, so that the influence on the rigidity of the sealing surface is reduced. The force of the joint of the disc can be neglected, focusing on the superposition of the medium pressure on the elliptical surface and the torque of the valve stem, and the effect on the pressure acting on the sealing surface.
The three eccentric butterfly valve are plate-like structures, and the middle part can be analyzed according to the plate problem. However, the spatial structure of the edge of the disc is more complicated, and the stress and deformation distribution on the edge have a great influence on the performance of the butterfly valve. The degree of fit of the sealing surface and the smoothness of the opening and closing are related to the force displacement distribution of the edge of the disc. In this paper, the edge of the disc is taken as the focus of analysis, and the load of the disc is deduced and calculated.
